Earlier quoted context omitted.
Does it make any sense to spin up your own little Mastodon server just for you and your most trusted friends, so you don't have to spend any time moderating content?
Yes, but the main problem is that Mastodon is very large and fat. Running it for more than a few people is expensive. There's also Pleroma (the Akkoma fork is recommended) and Misskey. There are people working on server software to be fully a part of Mastodon without spending $30/month. It should be possible to do this much more efficiently.
Finally an honestly named piece of software.
If I'm already running a moderately sized $30-or-so-per-month server with its own local database process, that's not very busy. Should it fit on that kind of system just fine, or does it need a lot of CPU, memory, disk space, and/or network bandwidth? Or do you think I'd have to upgrade to a 50-or-so-per-month server?
Again, not planning on having many people use it, but I'm just wondering how much baseline and peak overhead there is to just being on the network, along various dimensions.